The man accused of engineering the worst atrocities in Europe since World War II is finally behind bars.

Slobodan Milosevic, who ignited a decade of ethnic conflict in the name of Serbian nationalism, held police commandos at bay for 36 hours before he finally surrendered yesterday and was taken to jail in Belgrade.

He was charged with abuse of power and corruption - to which he pleaded not guilty. But he will almost certainly also face charges at the international war crimes tribunal, which could spur action against other key figures who remain at large.

"This will open the road to other arrests," says Florence Hartmann, spokeswoman for war-crimes chief prosecutor Carla del Ponte. "They have begun to cooperate, and this is a starting point. It is a very good first step."

The Belgrade drama unfolded as an American deadline passed for the Yugoslav government of Vojislav Kostunica - who ousted Mr. Milosevic in a popular revolt last October - to prove it was cooperating with the tribunal or risk losing half of a $100 million aid package. Washington has said it will judge Belgrade's compliance today.

Officials voiced relief that Milosevic was arrested without bloodshed, and that the first real step in reconciliation has begun. But observers warn that a broader social reckoning of crimes committed in the name of Serbian nationalism is a long way off.

"The Milosevic story is about the [nationalist] idea, and it still lives," says Milivoje Calija, managing director of the independent B-92 radio in Belgrade. "I'm afraid that for a few years we will have a reversal, in which common people will admire Milosevic as a guy with guts, who resisted the world, in the same way the French revere Napoleon, and some Russians love Stalin."

Milosevic set off his decade-long nationalist project with great fanfare in 1989. He gave a fiery speech on the 600th anniversary of a spectacular Serb defeat at the hands of Turkish troops at Kosovo Polje, the field in Kosovo where it took place.

Milosevic spoke of the "talismanic power" of nationalism, the need to fight for "Greater Serbia," and promised Serbs that "nobody has the right to beat you." Communist dictator Josip Broz Tito's efforts at forging ethnic unity dissolved overnight.

"It all started like Hitler - he was immensely popular, and many in the intelligentsia thought he would restore dignity to the Serbian people," says Vojin Dimitrijevic, head of the Belgrade Center for Human Rights.

Milosevic's militant Serbian agenda led to four Balkan wars that cost the lives of a quarter-million people and displaced hundreds of thousands more in Croatia, Bosnia, and Kosovo.

Those events added the words "ethnic cleansing" to the lexicon of war, and resulted in scores of tribunal indictments, which include genocide and other crimes in Croatia and Bosnia.

Mr. Kostunica, a constitutional lawyer, has been accused of taking an overly legalistic approach to Milosevic's case. He has criticized the tribunal as a biased instrument of American power - long a widely held view here.

But officials have taken several steps in recent weeks toward cooperating with the tribunal. An indicted Bosnian Serb official was handed over, and Belgrade sources say that wartime Bosnian Serb leaders Radovan Karadzic and Ratko Mladic - accused of ordering some of the worst atrocities of the Bosnian war - were recently asked to leave Belgrade.

And polls show the public attitude is changing. "Slowly, the nationalist right wing is backing Kostunica," says Milos Vasic, founder of the Belgrade weekly Vreme. He adds, however, that Kostunica's self-styled "moderate nationalism" can be just as dangerous.

Only a few hundred Milosevic loyalists turned up outside his suburban villa to support him, chanting "Slobo, Slobo!" and defending the man they deem the greatest Serbian patriot. That street support had evaporated by the time Milosevic game himself up. But one protester, Branka Djuric said, "These new leaders are slaves to the American government. It's shameful."

During the siege late Saturday, Kostunica made clear that no citizen is above the law. "It's clear that no man, not even Slobodan Milosevic, is worth civil strife and bloodshed," the president said.

Yugoslav Interior Minister Dusan Mihajlovic says there are no plans yet to send Milosevic to The Hague. Other officials do not rule it out, though, and suggest that it may be inevitable after a trial in Serbia.

"People are becoming aware that the old regime of Milosevic made many, many big mistakes, not only against the Serbian people, but across Yugoslavia," says Vladimir Goati, a political scientist at Belgrade University's Institute of Social Sciences.

The May 1999 Hague indictment describes Milosevic's command role in a "campaign of terror and violence against Kosovo Albanians." Tribunal prosecutors say the charge sheet could be expanded to include Bosnian crimes and genocide.

Government officials have insisted that no Serb suspects will be handed over to the court, at least until a new law - facing tough parliamentary opposition - is passed regulating cooperation with the tribunal.

Yugoslavia and its principal component, the republic of Serbia, said 10 days ago that Ms. del Ponte can begin to gather evidence in Serbia even before the law is passed. Del Ponte is awaiting official ties between Belgrade and the tribunal, however, before sharing evidence she has gathered on Milosevic's foreign bank accounts. This evidence is likely to be of considerable interest to Yugoslav prosecutors bringing their corruption case against the former Yugoslav leader.

Privately, though, court officials worry that Milosevic's Belgrade trial might be used to delay his transfer to The Hague.

"The local judicial proceedings are quite legitimate," says Ms. Hartmann, "but both procedures must be respected. We want to see him in The Hague."

Alex Todorovic in Belgrade and Peter Ford in Paris contributed to this report.